The thing is you can't change her name to married name becos you are not married yet and do not try to stick the passport as they might think it has been tampered with.

So the last thing you have got to do is to get a replacement in the Philippine Embassy in London. It might take 6-8 weeks before her new passport arrives but that's all you can do for now. They won't keep the old passport, they will give it back to you so don't worry about the visa etc on your wife's old passport.